Ionic Liquids Containing a Sulfonate Anion

ABSTRACT

The present invention relates to novel ionic liquids comprising a docusate, docusate variant, or other sulfonate anion. The ionic liquids may be conveniently made via, for example, metathesis. The ionic liquids are often hydrophobic and useful in many hydrocarbon compositions, polymer compositions, and in supercritical carbon dioxide applications. The ionic liquids are capable of hindering static electricity buildup in the hydrocarbon compositions and can therefore minimize flammability and/or explosiveness.

RELATED APPLICATION DATA

The present application is a continuation of U.S. patent applicationSer. No. 10/642,438, filed on Aug. 15, 2003; which claims priority toU.S. Provisional Application No. 60/404,178, filed Aug. 16, 2002 andU.S. Provisional Application No. 60/404,202, filed Aug. 16, 2002.

FIELD OF THE INVENTIONS

The present inventions pertain to compositions comprising an ionicliquid comprising a Docusate anion, a docusate variant anion, or othersulfonate anion, and processes for making said compositions.

BACKGROUND AND SUMMARY OF THE INVENTIONS

Ionic liquids are salts that are liquid at ambient or near ambienttemperatures. Ionic liquids have a number of uses that include replacingorganic solvents in chemical processes and reactions, extracting organiccompounds from aqueous waste streams, and as electrolytes in devicessuch as capacitors and batteries. This is because, unlike conventionalorganic solvents, ionic liquids are non-volatile and non-flammable.These properties are advantageous to help reduce losses to evaporation,eliminate volatile organic emissions, and improve safety.

Other properties of ionic liquids have also proved advantageous. Forexample, many ionic liquids have a broad temperature range at which theyremain liquid and also are stable over a broad pH range. This isbeneficial for high temperature processes with a demanding pH. Further,some ionic liquid systems can be used as both a solvent and catalyst.For example, [bmim]-Al₂Cl₇ and [emim]-Al₂Cl₇ can be employed as asolvent and catalyst in Friedel-Crafts reactions wherein bmim is1-butyl-3methylimidazolium and emim is 1-ethyl-3-methylimidazolium.

For the aforementioned reasons, it would be desirable to discover newionic liquid compounds with advantageous properties. It would further bedesirable if such compounds could be made by simple processes with lowamounts of waste and impurities.

Advantageously, new ionic liquid compounds have been discovered. Thecompounds comprise either a docusate or other sulfonate anion and aremade via simple processes that are capable of producing ionic liquidshaving a high purity.

DETAILED DESCRIPTION OF THE INVENTIONS

As used herein “ionic liquid” means a salt comprising a cation and ananion. The salt (or hydrate or solvate of the salt) is a liquid atambient or near ambient temperatures (i.e., having a melting point, ormelting range, less than about 100° C.). An ionic liquid may comprisetwo or more different salts, e.g., mixtures of salts comprising two ormore different cations, anions, or both. The ionic liquids of thepresent inventions are often hydrated or solvated. Thus, both hydratesand solvates are considered to be within the definition of “ionicliquid.”

As used herein “hydrophilic ionic liquid” means an ionic liquid which ispartially or wholly miscible with water.

As used herein “hydrophobic ionic liquid” means an ionic liquid which isrelatively immiscible with water, i.e., forms two phases at ambientconditions.

As used herein “composition” includes a mixture of the materials thatcomprise the composition, as well as, products formed by the reaction orthe decomposition of the materials that comprise the composition.

As used herein “derived from” means made or mixed from the specifiedmaterials, but not necessarily composed of a simple mixture of thosematerials. Substances “derived from” specified materials may be simplemixtures of the original materials, and may also include the reactionproducts of those materials, or may even be wholly composed of reactionor decomposition products of the original materials.

As used herein “halo” means chloro, bromo, fluoro, or iodo, arylenemeans a divalent aromatic group such as phenylene, napthylenylene,biphenylene, antracenylene, phenanthrenylene, etc., heteroarylene meansa divalent heteroaromatic group such as pyrrolene, furanylene,thiophenylene, pyridinylene, etc., alkylene means a divalent alkanegroup which may be substituted with one or more heteroatoms such asnitrogen or oxygen, cycloalkylene means a divalent cycloalkane groupwhich may be substituted with one or more heteroatoms such as nitrogenor oxygen, alkenylene means a divalent alkene group which may besubstituted with one or more heteroatoms such as nitrogen or oxygen.

As used herein “Docusate” is the anion of the bis(2-ethylhexyl)ester ofsulfosuccinic acid. The chemical formula of Docusate (anion) isC₂₀H₃₇O₇S⁻. As used herein, “docusate variant” is taken to include thecompounds described by chemical structures I and III described below andincludes the anions of bis(organo)ester derivatives of sulfosuccinicacid and anions of bis(organoamide) derivatives of sulfosuccinic acid.

Any numerical values recited herein include all values from the lowervalue to the upper value in increments of one unit provided that thereis a separation of at least 2 units between any lower value and anyhigher value. As an example, if it is stated that the amount of acomponent or a value of a process variable such as, for example,temperature, pressure, time and the like is, for example, from 1 to 90,preferably from 20 to 80, more preferably from 30 to 70, it is intendedthat values such as 15 to 85, 22 to 68, 43 to 51, 30 to 32 and the like,are expressly enumerated in this specification. For values which areless than one, one unit is considered to be 0.0001, 0.001, 0.01 or 0.1as appropriate. These are only examples of what is specifically intendedand all possible combinations of numerical values between the lowestvalue and the highest value enumerated are to be considered to beexpressly stated in this application in a similar manner.

The ionic liquid of the present invention comprise one or morecompounds. Thus, the ionic liquid may be a pure compound or may be amixture of compounds. Each compound comprises an anion or a mixture ofanions and a cation or a mixture of cations as described below.

Anions

Exemplary anions of compounds of the instant invention include thosehaving a chemical structure selected from

R₁—O—C(O)—CH(SO₃ ⁻)—R₃—C(O)—O—R₂; and  I

R₁, R₂, R₄ and R₅ in Structure I and II above are independently selectedfrom the group consisting of substituted or unsubstituted alkyl oralkenyl groups. The alkyl or alkenyl

groups of R₁, R₂, R₄ and R₅ should have a sufficient number of carbonatoms so that the ionic liquid has the desired properties. For example,if a hydrophobic ionic liquid is desired then the total number of carbonatoms in the ionic liquid will typically be more than if a hydrophilicionic liquid is desired. However, if there are too many carbon atoms inthe anion then the ionic liquid may be less useful as an ionic liquiddue to a decline in properties such as vapor pressure, dipole moment,polarity, etc.

For hydrophobic ionic liquids R₁, R₂, R₄ and R₅ are preferablyindependently selected from alkyl groups having about five or morecarbon atoms, preferably from about six to about eighteen carbon atoms.One preferable group for R₁, R₂, R₄ and R₅ is—CH₂—CH(CH₂CH₃)(CH₂CH₂—CH₃). This group is useful for the properties itgives to the ionic liquid and for its cost and convenience tomanufacture.

R₃ in structure I above is a substituted or unsubstituted alkylenegroup, heteroarylene group, arylene group, or cycloalkylene group.Preferably R₃ is a substituted or unsubstituted alkylene group and evenmore preferably R₃ is —(CH₂)_(n)— wherein n is an integer of from aboutone to about 10.

R₆, R₇, and R₈ are independently selected from hydrogen (H) or anothersubstituent such as, for example, alkyl, NO₂, halo, cyano, silyl, andOH. Preferably, R₆, R₇, and R₈ are H.

In some instances, two or more adjacent substitutents such as or R₁ andR₂, R₄ and R₅, R₆ and R₇, and/or R₇ and R₈ may be taken together to forma ring such as a 5-7 membered carbocyclic ring. Examples of suchcarbocyclic rings include cyclopentyl and cyclohexyl rings.

R₁, R₂, R₃, R₄, R₅, R₆, R₇, and R₈ may optionally be substituted withone or more substituents. The type of the substituent is notparticularly critical so long as the compound or mixture of compoundshas the desired ionic liquid properties. Thus, the substituents usuallyinclude typical and non-typical organic substituents such as thoseselected from the group consisting of alkyl, NO₂, halo, cyano, silyl,OH, and other suitable substituents. The substituent group itself mayoften be further branched.

Another exemplary anion that can be used to make ionic liquids is adocusate variant having the following chemical structure:

R₁—N(R₂)—C(O)—CH(SO₃ ⁻)—R₃—C(O)—N(R₄)—R₅  III

R₁, R₂, R₃, R₄, and R₅ in chemical structure III can be independentlyselected from a hydrogen atom (H) or a carbon-containing group, e.g.,alkyl, alkenyl, alkynyl, aryl, benzyl, alkyl-ether, etc.

In an embodiment, the anion source is a sodium salt of the 2-ethylhexylamide sulfonate salt, which can be synthesized using known techniqueshaving the benefit of this Specification. For example, an anion wasprepared having the above chemical structure III with R₁ and R₅ eachbeing a 2-ethylhexyl group, R₂ and R₄ each being a hydrogen atom, and R₃being a methylene group. Two different ionic liquids were prepared usingthis anion by first isolating it as a sodium salt and then reacting itwith a source of two different cations. The cation in one of the ionicliquids was tetrabutylammonium cation. The cation in the other ionicliquid was 1-methyl-3-hexyl imidazolium.

In other experiments, a second anion was prepared having the abovechemical structure III with R₁ and R₅ each being a 2-ethylhexyl group,R₂ and R₄ each being an ethyl group, and R₃ being a methylene group. Twomore ionic liquids were prepared using this anion by first isolating itas a sodium salt and then (in separate experiments) reacting it with asource of the same two cations mentioned above, namelytetrabutylammonium cation and 1-methyl-3-hexyl imidazolium.

Based upon experiments in which ionic liquids have been made from anionshaving chemical structure III, it is believed that, as is the case withthe docusate salts and their derivatives and variants, each of the Rgroups in chemical structure III could vary in length or composition andstill give rise to an ionic liquid when combined with an suitablecation, e.g., an onium cation.

Cations

The cation of the ionic liquid to be produced is not particularlycritical so long as the ionic liquid has properties to make it suitablefor its intended use. Typical useful cations include, for example,“onium” cations. Onium cations include cations such as substituted orunsubstituted ammonium, phosphonium, and sulfonium cations. Preferredonium cations include, for example, substituted or unsubstituted N-alkylor N-aryl pyridinium, pyridazinium, pyrimidinium, pyrazinium,imidazolium, pyrazolium, thiazolium, oxazolium, triazolium,imidazolinium, methylpyrrolidinium, isothiazolium, isoxazolium,oxazolium, pyrrolium, and thiophenium. The substituents include one ormore of the following groups: halo, alkyl, and aryl groups such asphenyl. In addition, two adjacent substituents may be joined together toform an alkylene radical thereby forming a ring structure converging onN. The alkyl, phenyl, and alkylene radicals may be further substituted.Another particularly preferred cation is an ammonium cation substitutedby one or more groups such as alkyl and aryl groups such as phenyl. Manysuch cations and substituted cations are described in U.S. Pat. Nos.5,827,602 and 5,965,054, which are incorporated by reference in theirentirety.

Other suitable cations include BMIM, tetrabutyl ammonium, tributylmethylammonium, tetrabutyl phosphonium, tetraethyl ammonium, N,N-dialkylpyrrolidinium, trimethyl 2-hydroxyethyl ammonium, N,N′-dialkylimidazolium, N-alkylpyridinium, or mixtures thereof. The cation may bean onium cation and optionally contains more than 4 carbon atoms.

Processes to Make Compounds Having Structures I-III and Mixtures Thereof

The ionic liquid compounds of structures II may be conveniently made bya number of different processes. One process which is suitable formaking hydrophobic or hydrophilic ionic liquids or mixtures of thepresent invention comprises using metathesis, i.e., a doubledecomposition reaction, whereby the reaction of two or more compoundsforms two or more new compounds—one of which is the ionic liquid. Forexample, reacting [bmim]Cl with sodium docusate will yield[bmim]docusate and NaCl. The two or more compounds produced by themetathesis reaction can then be separated by any means.

The manner of contacting the two or more compounds to form the ionicliquid is not particularly important so long as the desired reactionoccurs. Generally, the compounds can be mixed in any order, can beformed in situ, or can be mixed together with a solvent such as waterwhich is at least partially miscible and does not significantly reactwith any of the compounds.

The starting compounds are often readily available and, in addition,many syntheses are available to those skilled in the art to make thedesired starting compounds. The mixing conditions may vary depending onthe specific compounds employed and the desired product. In mostinstances, it is acceptable to contact the compounds and an optionalsolvent such as water or dichloromethane at ambient pressure and atemperature high enough for the reaction to occur efficiently but not sohigh as to decompose or boil off any starting compound. Generally, thecontacting temperature may range from about 75 to about 110° C.,preferably from about 85 to about 100° C. When water is used as asolvent, temperatures of about 75 to about 110° C. are sometimespreferable because this tends to breaks up emulsions which typicallyform between the ionic liquid and water. On the other hand, when thesolvent is organic (e.g., dichloromethane), the preferred temperature istypically substantially lower, usually around room temperature, e.g.,25° C. or slightly above room temperature.

The manner in which the increased temperature is achieved and maintainedis not particularly critical. Often any heating element may be employedas the compounds are mixed or the starting compounds can be heatedseparately and then mixed. Similarly, any vessel or reactor can beemployed so long as it is of adequate size and material. Often it isbeneficial to employ a stirring means to facilitate the reaction.

Generally, the increased temperature is maintained for at least asufficient time until the desired reaction has occurred to the desiredextent. In some instances, it may be desirable to maintain the increasedtemperature for a longer time than it takes to complete the reaction. Inthis manner, any water or lower boiling components that are formed asbyproducts or present as solvents can be removed by boiling.

The amount of each of the starting compounds may vary depending upon thedesired yield. In general, high yields are often obtained by using aboutthe stoichiometric amount of reactants, i.e., about a 1:1 ratio.However, as one skilled in the art will appreciate, different reactionconditions may alter the ratio of reactants at which the optimum yieldoccurs.

If one desires to make an ionic liquid mixture comprising two or moredifferent salts, then it can be accomplished by employing a mixture ofthree or more different compounds so that a variety of salts are formed.The resulting ionic liquid salt mixture can then be used as a mixtureor, if desired, individual salts can be separated by routine means.

If necessary, the ionic liquid or ionic liquid mixture may be recoveredfrom the solvent and/or reaction mixture by any suitable means the mostefficient of which may vary depending upon the type and desired purityof the ionic liquid or mixture. Suitable means of recovery includerotary evaporation or distillation, azeotropic distillation, ionchromatography, liquid liquid extraction, crystallization,pervaporization, drying agents, and reverse osmosis.

While the aforementioned process may be employed to make hydrophobic orhydrophilic ionic liquids, in some applications it is preferable to makehydrophobic ionic liquids. This is because hydrophobic ionic liquids areoften not very soluble in the water which is often used as a reactionmedium. Therefore, simple liquid-liquid extraction can be used toseparate the hydrophobic ionic liquid from the soluble byproduct. Incontrast, hydrophilic ionic liquids are often miscible with thebyproduct. Consequently, a different separation method, e.g., solventextraction, can be employed. For example, it may be desirable ornecessary to use a hydrophobic solvent like an alkyl chloride, e.g.methylene chloride, to extract the ionic liquid.

Characteristics and Uses of Ionic Liquids of the Present Invention

The purity of ionic liquids produced by the processes of this inventioncan often be greater than 55%, preferably greater than 60%, morepreferably greater than 70%, most preferably greater than 80%. This isoften advantageous for processes that require high purity materials suchas in the electronics industry. The ionic liquids are also preferablyhydrophobic and thus useful in many processes as a substitute for anorganic solvent and in mixtures with catalysts such as ZnCl₂, CuCl₂,AlCl₃, and organic catalysts.

The ionic liquids of the present invention are also often useful inmixtures with hydrocarbons such as alkanes, e.g., hexane. The mixturesoften do not hold static electricity charge and thus will not ignite orexplode readily.

Docusate and Docusate Variants in Supercritical CO₂ Applications

It has been found that tetrabutylammonium docusate is soluble insupercritical carbon dioxide (C %). Supercritical applications using CO₂typically operate at temperatures between above 32° C. and pressuresabove about 1,070 psi. It is believed that the docusate and docusatevariant based ionic liquids are useful adjuvants, additives, anddetergents for addition to supercritical CO₂ for cleaning, synthesis,and separations applications.

Docusate and Docusate Variants as Anti-Static Agents

It is believed that the docusate and docusate variant based ionicliquids are useful antistatic additives for fuel applications andpolymer applications. The docusate and docusate variant based ionicliquids tend to be partially or fully miscible with hydrocarbons (e.g.,alkanes such as hexane) and can be added to fuels as anti-staticadditives. These ionic liquids can also be added to polymers, e.g.,polyvinylacetate, as an anti-static additive.

Docusate and Docusate Variants in Ionic Liquid Blends

In one embodiment, two or more ionic liquids are blended together toform an improved reaction solvent. It is believed that Lewis Acid ionicliquids can be advantageously blended with ionic liquids based upondocusate or docusate variants to form an improved reaction solvent thatprovides better mixing between reactants to improve reaction kinetics.Because the docusate and docusate variant ionic liquids tend to be atleast relatively miscible with the hydrocarbon streams, they tend toinhibit the formation of two phases and improve the mixing and contactbetween the reactants. Examples of Lewis Acid ionic liquids that arebelieved to be useful in making blends with the sulfonate anion (e.g.,docusate and docusate variant) ionic liquids of the present inventionare disclosed in copending U.S. Application entitled “Lewis Acid IonicLiquids,” filed on Aug. 15, 2003 and invented by Roger Moulton (SerialNo. currently unknown), which is incorporated by reference as if fullyset forth herein.

Exemplary Lewis Acid ionic liquids useful in these blends include ionicliquids having (i) a cation selected from ammonium, sulfonium, andphosphonium cations and having less than 14 total carbon atoms; and (ii)an anion having the formula AlyR3y+1 wherein y is greater than 0 and Ris independently selected from the group consisting of an alkyl groupand halogen group. A suitable anion for the Lewis Acid ionic liquid inthe blend is aluminum chloride anion.

A suitable cation for the Lewis Acid ionic liquid is tetraalkylammonium.Depending on the desired ionic liquid properties it may be advantageousfor one or more of the alkyl groups to be optionally substituted withone or more suitable substitutents. Suitable substituents include, forexample, halogens such as chloride, bromide, or iodide. Particularlypreferred tetraalkylammonium cations include trimethylethyl ammonium,trimethyl chloromethyl ammonium, trimethylbutyl ammonium, and tributylmethyl ammonium.

Another suitable cation for the Lewis Acid ionic liquid are the N-alkylsubstituted saturated heterocycles such as piperidinium andmorpholinium. In particular, piperidinium substituted on the nitrogenwith an alkoxy or alkyl group such as —(CH₂)₂OMe, butyl, or propyl areparticularly beneficial. Pyrrolidine-based cations can also be employed.The cation may include ether functionality (e.g., NCH2CH2OCH3⁺). Thecation may include halogenated alkyl groups.

Exemplary Lewis Acid ionic liquids for the blend include ionic liquidshaving an aluminum chloride anion and a cation sourced from an ammoniumsalt such as MeBu3N Cl, Me3PentylN Cl, Me3ButylN Cl, MeEt3N Cl, Me2Et2NCl, Cl—CH2-NMe3 Cl, or N-methyl-N-Butyl Pyrrolidinium Cl. Otherexemplary Lewis Acid ionic liquids include N-alkyl substitutedpiperidinium heptachlorodialuminate, trimethyl chloromethyl ammoniumheptachlorodialuminate, trimethylbutyl ammonium heptachlorodialuminate,and tributyl methyl ammonium heptachlorodialuminate.

The following examples are not intended to limit the invention, butrather, are intended only to illustrate a few specific ways the instantinvention may be employed.

Example 1 Synthesis of Tetrabutylammonium Docusate

1 mole sodium docusate (444 grams) was dissolved in 2 liters water, andthen 1 mole tetrabutylammonium bromide (321 grams) was added as a solid.After stirring for a few minutes, the stirring was stopped and thesolution separated into two layers. The top layer was collected in aseparatory funnel. It was washed twice with 1 liter of water, and heatedto 100° C. to facilitate phase disengagement. The resultingtetrabutylammonium docusate was heated to 110° C. to drive off anydissolved water in it. The yield was nearly quantitative (624 grams, 94%yield).

Examples 2-5

The ionic liquids of Examples 2-5 in Table 1 below were madesubstantially as in the same manner as Example 1 except thatapproximately 1 mole of the starting material in Table 1 was substitutedfor the 1 mole of tetrabutylammonium bromide in Example 1.

TABLE 1 Solubility Example Starting Material Ionic Liquid in water 2Me(n-Bu)₃N Br Me(n-Bu)₃N Docusate Hydrophobic 3 Me₃N(CH₂)₆NMe₃ BrMe₃N(CH₂)₆NMe₃ Hydrophobic Docusate 4 n-Bu₄P Br n-Bu₄P DocusateHydrophobic 5 Et₄N Br Et₄N Docusate miscible

Examples 6-10

The ionic liquids of Examples 6-10 in Table 2 below were made bydissolving sodium docusate in dichloromethane and in a separate flaskdissolving the starting material of Table 2 in dichloromethane. The twosolutions were mixed and stirred for approximately 12 hours. Thesolutions were then filtered to remove precipitated solid salts, thenevaporated to thick syrups. The thick syrups are then extracted withdiethyl ether, hexanes or a mixture thereof; again filtering to removedsolid salts. After rotary evaporation, the residues are redissolved inhexane/ether and the process of filtration repeated (using progressivelysmaller fractions of ether in the mix) until no further solids wereformed. The resulting salts are then washed with water to effect a finalremoval of inorganic salts, after which they are dried in vacuo.

TABLE 2 Example Starting Material Ionic Liquid 6 1-n-hexyl-3-methyl1-n-hexyl-3-methyl imidazolium imidazolium bromide docusate 71-n-octyl-3-methyl 1-n-octyl-3-methyl imidazolium imidazolium bromidebromide docusate 8 1-n-butyl-3-methyl 1-n-butyl-3-methyl imidazoliumimidazolium bromide docusate 9 1-methyl-2-ethyl 1-methyl-2-ethylimidazolium imidazolium bromide docusate 10 tetra-n-butylammoniumtetra-n-butylammonium docusate bromide

The ionic liquids of Examples 6-10 were generally hydrophobic ionicliquids. In the case of Example 6, 1-hexyl-3-methyl imidazoliumdocusate, contacting it with 40 volume percent or less of water resultedin the formation of two phases, even after agitation. However, when1-hexyl-3-methyl imidazolium docusate was contacted with 50 volumepercent water, agitation produced a stiff, visibly monophasic gel.Addition of additional water to the gel, followed by agitation, resultedin the formation of two phases again. While not wishing to be bound byany particular theory, it is believed that some of the ionic liquids ofthe present invention may become hydrated or solvated when mixed withsome proportions of water. This results in an ionic liquid which isinsoluble and forms two phases when mixed with some proportions withwater and is a single phase at other proportions. This unique behaviorcould be very beneficial for some applications in which solubility orinsolubility with water is important.

Example 11

This example details the synthesis of a tetrabutyl ammonium molten saltof the amide having chemical formula III above. One-tenth of a mole (50g) of the sodium salt of the amide-sulfonate salt having chemicalstructure III above (with R₂ and R₄ being CH₂CH₃, R1 and R5 each being a2-ethylhexyl group, and R₃ being CH₂) was dissolved in 250 mL ofdichloromethane, and one-tenth mole (32 g) of tetrabutyl ammoniumbromide was added as a solid. The mixture was stirred for a day, afterwhich time the solution was filtered first through filter paper and thenthrough a short plug of silica gel. The eluted dichloromethane solutionwas quickly washed with water, dried over magnesium sulfate, and thesolvent removed in vacuo, leaving the desired product in high yield (64g, 89%). The product salt is soluble in both water and in several commonorganic solvents, such as dichloromethane and acetone. The melting rangeof the resulting salt was less than about 30° C. because the product wasa viscous oil at room temperature. The product salt included Bis(N-ethyl-N-(2-ethylhexyl)sulfosuccinate diamide) anion paired withtetrabutyl ammonium cation.

Examples 12-19

These examples detail the preparation of an ionic liquid from a sodiumsalt of the sulfosuccinate salts, which are docusate variants. Theesters were then combined with an onium cation to make an onium moltensalt.

Ten grams (0.03 mol) of tetrabutylammonium bromide was dissolved in 50mL of water, and to the stirred solution was added as a solid twelvegrams (0.03 mol) of the sodium salt of the di-n-hexyl ester ofsulfosuccinic acid. (By “di-n-hexyl ester of sulfosuccinic acid” it ismeant that the sulfosuccinic acid molecule is esterified on the twocarbonyl groups of the sulfosuccinic molecule and not at the sulfonicgroup). After stirring for a few minutes, the water layer was extractedwith three successive 50 mL portions of dichloromethane, which werecombined, dried with anhydrous magnesium sulfate, and evaporated,leaving the desired product (13 g, 73% yield). The melting range of theresulting salt was less than about 30° C. because the product was aviscous oil at room temperature.

The same experimental procedure was used to prepare ionic liquids of thetetrabutyl ammonium cation with the sodium salts of the followingdocusate variants: (i) di-n-cyclohexyl ester of sulfosuccinic acid; (ii)di-n-octyl ester of sulfosuccinic acid; (iii) di-n-butyl ester ofsulfosuccinic acid; (iv) di-isobutyl ester of sulfosuccinic acid; (v)di-neopentyl ester of sulfosuccinic acid; (vi) di-n-heptyl ester ofsulfosuccinic acid; and (vii) di-n-heptyl ester of sulfosuccinic acid.The melting range of the resulting salts was less than about 80° C. andtypically between about 40° C. and 80° C. The octyl and heptyl docusatevariants had lower melting ranges as indicated by the fact that theywere a viscous liquids at room temperature.

Representative NMR Data

The structure and composition of the ionic liquids was determined by1H-NMR spectroscopy. For all docusate salts (2-ethylhexylsulfosuccinatediester), the spectra consist simply of resonances arising from theanion superimposed on those of the cation. For all docusate salts,resonances originating from the anion were (with minor variations)within the following ranges: (300 Mhz, CDCl₃, d: 0.73-0.83 (triplets),1.24-1.70 (overlapping multiplets), 3.05-3-31 (complex m), 3.90-4.25(overlapping m)

Cation resonances (300 MHz, CDCl₃, d): (1-methyl-3-hexyl imidazolium):0.79 (t), 1.21-1.27 (overlapping m), 1.80 (m), 4.03 (s), 4.22 (t), 7.35(s), 7.49 (s), 9.50 (s).

(tetraethylammonium): 1.32 (t), 3.34 (q)

(tetrabutylammonium): 1.03 (t), 1.20-1.40 (overlapping m), 3.23 (q)

(tetraoctylammonium): 0.86 (t), 1.18-1.50 (overlapping m), 3.25 (q)

(N-methyl-N—(CH2CH2OCH2CH3)pyrrolidinium): 0.86 (t), 1.31 (m), 2.11 (m),3.0-4.2 (complex overlapping m)

(trimethylhexadecylammonium): 0.87 (t), 1.20-1.60 (overlapping m), 2.13(s), 3.15 (q)

(methyltributylammonium): 0.84 (t), 1.23-1.70 (overlapping m), 2.20 (s),3.24 (m)

(1,2-bis(tributylammonium)ethane): 0.83 (t), 1.22-1.58 (overlapping m),2.20 (s), 3.22 (m)

Ionic liquids of several docusate variants were also made. The NMRspectra of these salts, like those of the docusate derivatives, consistof the spectrum of the specific anion overlayed on that of the specificcation. Below are the NMR data for the tetrabutylammonium derivatives ofthree docusate variant salts. For each salt, the resonances arising fromthe cation comport with those of the tetrabutyl ammonium cation ofdocusate, the values for which are listed above. Below are theresonances from the anion of these example salts (300 MHz, CDCl3, d):

Bis (n-hexylsulfosuccinate diester): 0.84 (t), 1.2-1.4 (overlapping m),1.6 (m), 3.07 (m), 4.05-4.22 (overlapping m).

Bis (cyclohexylsulfosuccinate diester): 1.2-1.8 (complex overlapping m),3.10 (m), 4.2-4.8 (overlapping m)

Bis (neopentylsulfosuccinate diester): 0.87 (s), 0.90 (s), 3.05-3.25(overlapping m), 3.78 (s), 3.80-3.93 (m), 4.23-4.29 (m)

Bis (N-ethyl-N-(2-ethylhexyl)sulfosuccinate diamide): 0.75-0.88(triplets), 1.21-1.78 (overlapping multiplets), 2.24 (m) 3.11-341(complex m), 3.86-4.45 (overlapping m)

1-59. (canceled)
 60. A composition comprising an ionic liquidcomprising: (a) a substituted or unsubstituted ammonium cation; and (b)an anion having the structure (I):R₁—O—C(O)—CH(SO₃ ⁻)—R₃—C(O)—O—R₂  I wherein, R₁ is selected from thegroup consisting of substituted or unsubstituted alkyl or alkenyl groupsconsisting of from about six to about eighteen carbon atoms; R₂ isselected from the group consisting of substituted or unsubstituted alkylor alkenyl groups consisting of from about six to about eighteen carbonatoms; and R₃ is a substituted or unsubstituted alkylene group.
 61. Thecomposition of claim 60, wherein the ammonium cation is substituted withone or more alkyl groups.
 62. The composition of claim 60, wherein theammonium cation contains more than 4 carbon atoms.
 63. The compositionof claim 60, wherein R₁ is substituted or unsubstituted alkyl.
 64. Thecomposition of claim 60, wherein R₁ is alkyl-substituted alkyl.
 65. Thecomposition of claim 60, wherein R₁ is —CH₂—CH(CH₂CH₃)(CH₂CH₂—CH₃). 66.The composition of claim 60, wherein R₂ is substituted or unsubstitutedalkyl.
 67. The composition of claim 60, wherein R₂ is alkyl-substitutedalkyl.
 68. The composition of claim 60, wherein R₂ is—CH₂—CH(CH₂CH₃)(CH₂CH₂—CH₃).
 69. The composition of claim 60, wherein R₃is —(CH₂)_(n)—; and n is 1, 2, 3, 4, 5, 6, 7, 8, 9 or
 10. 70. Thecomposition of claim 60, wherein the anion is selected from the groupconsisting of the anions of (i) di-cyclohexyl ester of sulfosuccinicacid; (ii) di-n-octyl ester of sulfosuccinic acid; (iii) di-n-butylester of sulfosuccinic acid; (iv) di-isobutyl ester of sulfosuccinicacid; (v) di-neopentyl ester of sulfosuccinic acid; (vi) di-n-heptylester of sulfosuccinic acid; and (vii) bis(2-ethylhexyl)ester ofsulfosuccinic acid.
 71. The composition of claim 60, wherein the anionis an anion of bis(2-ethylhexyl)ester of sulfosuccinic acid.
 72. Thecomposition of claim 60, wherein the ionic liquid is hydrophobic. 73.The composition of claim 60, wherein the composition is greater than 55weight percent ionic liquid.
 74. The composition of claim 60, whereinthe composition is greater than 70 weight percent ionic liquid.
 75. Thecomposition of claim 60, wherein the composition is greater than 80weight percent ionic liquid.
 76. The composition of claim 60, furthercomprising a hydrocarbon.
 77. The composition of claim 60, furthercomprising a catalyst.
 78. The composition of claim 60, furthercomprising CO₂ at supercritical conditions.
 79. The composition of claim70, further comprising a polymer.
 80. The composition of claim 60,wherein the anion and the ammonium cation are present in stoichiometricamounts.